Problem with the Router Board 112

RouterOS General
1

I configured link between two router boards 112. Some times later i faced to the problem: i cannot see in winbox mac address of one RB. I tried to reboot this RB. After rebooting, mac address of RB appeared in winbox and the same time is gone. I cannot connect to this RB. But i steel see another RB trought this one.

2

i found the problem